centre-left sphere sovereignty. [16] ISBN978-1-134-52146-3. | access-date = (help)^Müller, Jan-Werner (2014). ISBN978-1-4129-6427-2. (help) ISBN9781935955009. | access-date = (help)^abDussel, Enrique (1981). ISBN978-0-8028-2131-7. (help)^Lamberts, Emiel (1997). ISBN9789061868088. | access-date = (help)^Kerbo, Harold R.; Strasser, Hermann (2000). ISBN9780072928198. (help) ISBN978-1-134-81834-1. (help)^Schindler, Jeanne Heffernan (2008). ISBN9780739108840. | access-date = (help) ISBN9789053834589. (help)